Polyphenylene ether is useful as a resin material for molding because of its good mechanical and electrical properties. However, it has poor oil-resistance. In order to solve this disadvantage, it is known that polyphenylene ether can be blended with polyamide which is resistant to oil (see, for example, Japanese Patent Laid-Open No. 16525/1981). The resulting composition exhibits improved oil resistance as compared to polyphenylene ether alone. However, polyphenylene ether and polyamide show poor compatibility with each other and, accordingly, properties intrinsic to these two resins, e.g., the excellent mechanical properties, are not fully exhibited when the resins are combined.
In order to improve this, the attempt has been made to enhance impact resistance while obtaining improved oil resistance by adding a compound having (a) a carbon-carbon double or triple bond and (b) a carboxyl, acid anhydride, acid amide, imide, carboxylic ester or epoxy group (Japanese Patent Publication (unexamined) No.56-26913). However, shaped articles prepared from this composition have a tendency to show poor surface appearance.
Finholt (U.S. Pat. No. 3,379,792) discloses polymer blends wherein the processability of polyphenylene ether resins may be improved by blending with from 0.1 to 25% by weight of a polyamide. However, the advantages of the Finholt invention are limited by the fact that when the concentration of the polyamide exceeds 20% by weight, appreciable losses in other physical properties result. Specifically, there is no, or at best poor, compatibility between the polyphenylene ether and the polyamide such that phase separation of the resins occurs on molding or the molded article is inferior in mechanical properties.
Ueno et al. (U.S. Pat. No. 4,315,086) discloses polyphenylene ether blends having improved mechanical resistance without a loss of other mechanical properties by blending therewith a polyamide and a specific compound selected from the group consisting essentially of (A) liquid diene polymers, (B) epoxy compounds and (C) compounds having in the molecule both of (i) an ethylene carbon-carbon double bond or carbon-carbon triple bond and (ii) a carboxylic acid, acid anhydride, acid amide, imide, carboxylic acid ester, amino or hydroxy group.
Finally, Kasahara et al. (EP No. 46040) discloses the use of a copolymer comprising units of a vinyl aromatic compound and either an alpha, beta-unsaturated dicarboxylic acid anhydride or an imide compound thereof as a modifier to an impact resistant polyphenylene ether-polyamide blend for improved heat resistance and oil resistance.
Aycock et al. (U.S. Pat. No. 4,600,741) discloses the use of an acyl functional compatibilizer, preferably the reaction product of polyphenylene ether with trimellitic anhydride acid chloride, for polyphenylene ether-polyamide blends.